Ford Mustang 5.0L Engine Horsepower Modifications

Modding Your 5.0 With Bolt-Ons And Beyond

Richard Holdener

June 18, 2010

Modern modular motors have a lot going for them, especially with the recent introduction of the new 412hp 5.0L variant. Sharp-eyed readers will no doubt recognize that the Blue Oval marketing department took a retro step back because the original 5.0L had, and still has, such a strong following. In fact, 5.0L guys are diehard, often dismissing the modern mod motor for its lack of torque and the inherent limitations on displacement thanks to the diminutive bore centers.

Meanwhile, the trusty pushrod 5.0L has no such deficiencies, and can be taken to the high side of 370 ci with the proper combination of block, bore, and stroke. The limiting factor is actually the deck height. What the original 5.0L has over the modern machinery is also cost, as a 5.0L Mustang can be had for about the price of a decent value meal at your local fast food joint.

To illustrate just how receptive the original 5.0L is to modifications, we put one through the ringer on the engine dyno, running it with a myriad of modifications. We did eliminate a few tried and true mods, however, like the air silencer removal, mass air meters (we ran with a FAST management system), and underdrive pulleys. But it did allow us to run the full gamut of performance upgrades starting with a simple throttle body and ending with a complete turbo kit. Along the way we tried a pair of intake manifolds, performance aluminum heads and even nitrous. In short, it was a full day of dyno testing and part swapping, but what better way to spend the afternoon than watching the power needle climb and climb and climb?

Not wanting to limit ourselves with a stock (junkyard) 5.0L, we built a 302 capable of withstanding our eventual boosted output. To that end, we assembled a 302 using a factory 5.0L roller block machined by L&R and assembled by Demon Engines. The short-block consisted of a forged-steel crank from RPM, combined with a set of forged rods from ProComp and matching pistons from Probe Racing. The flat-top pistons yielded a static compression ratio of 9.35:1 with the 61cc chambers in the stock heads.

In addition to the stock heads, cam, and intake, the build up also featured new hydraulic roller lifters, a double-roller timing chain, and hardened pushrods (6.25-inch), all from Comp Cams. The stock E7TE heads had been previously modified to accept screw-in rocker studs, which we used with self-aligning roller rockers.

We hoped to test stock rockers versus the roller rockers, but the modified heads would no longer accept bolt-down rockers. Other than the screw-in studs and a spring upgrade (to work with the Xtreme Energy cam installed later), the head ports, chambers, and valve job remained completely stock, meaning they performed just like a stock set would in terms of flow and power.